// dear imgui: Renderer Backend for DirectX12
// This needs to be used along with a Platform Backend (e.g. Win32)

// Implemented features:
//  [X] Renderer: User texture binding. Use 'D3D12_GPU_DESCRIPTOR_HANDLE' as ImTextureID. Read the FAQ about ImTextureID!
//  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.

// Important: to compile on 32-bit systems, this backend requires code to be compiled with '#define ImTextureID ImU64'.
// This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
// This define is set in the example .vcxproj file and need to be replicated in your app or by adding it to your imconfig.h file.

// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
// Read online: https://github.com/ocornut/imgui/tree/master/docs

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2021-01-11: DirectX12: Improve Windows 7 compatibility (for D3D12On7) by loading d3d12.dll dynamically.
//  2020-09-16: DirectX12: Avoid rendering calls with zero-sized scissor rectangle since it generates a validation layer warning.
//  2020-09-08: DirectX12: Clarified support for building on 32-bit systems by redefining ImTextureID.
//  2019-10-18: DirectX12: *BREAKING CHANGE* Added extra ID3D12DescriptorHeap parameter to ImGui_ImplDX12_Init() function.
//  2019-05-29: DirectX12: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
//  2019-04-30: DirectX12: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
//  2019-03-29: Misc: Various minor tidying up.
//  2018-12-03: Misc: Added #pragma comment statement to automatically link with d3dcompiler.lib when using D3DCompile().
//  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
//  2018-06-12: DirectX12: Moved the ID3D12GraphicsCommandList* parameter from NewFrame() to RenderDrawData().
//  2018-06-08: Misc: Extracted imgui_impl_dx12.cpp/.h away from the old combined DX12+Win32 example.
//  2018-06-08: DirectX12: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle (to ease support for future multi-viewport).
//  2018-02-22: Merged into master with all Win32 code synchronized to other examples.

#include "imgui.h"
#include "imgui_impl_dx12.h"

// DirectX
#include <d3d12.h>
#include <dxgi1_4.h>
#include <d3dcompiler.h>
#ifdef _MSC_VER
#pragma comment(lib, "d3dcompiler") // Automatically link with d3dcompiler.lib as we are using D3DCompile() below.
#endif

#include "common/d3d12/texture.h"
#include "common/d3d12/context.h"

// DirectX data
static ID3D12Device* g_pd3dDevice = NULL;
static ID3D12RootSignature* g_pRootSignature = NULL;
static ID3D12PipelineState* g_pPipelineState = NULL;
static DXGI_FORMAT                  g_RTVFormat = DXGI_FORMAT_UNKNOWN;
static D3D12::Texture g_FontTexture;

struct FrameResources
{
  ID3D12Resource* IndexBuffer;
  ID3D12Resource* VertexBuffer;
  int                 IndexBufferSize;
  int                 VertexBufferSize;
};
static FrameResources* g_pFrameResources = NULL;
static UINT             g_numFramesInFlight = 0;
static UINT             g_frameIndex = UINT_MAX;

template<typename T>
static void SafeRelease(T*& res)
{
  if (res)
    res->Release();
  res = NULL;
}

struct VERTEX_CONSTANT_BUFFER
{
  float   mvp[4][4];
};

static void ImGui_ImplDX12_SetupRenderState(ImDrawData* draw_data, ID3D12GraphicsCommandList* ctx, FrameResources* fr)
{
  // Setup orthographic projection matrix into our constant buffer
  // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
  VERTEX_CONSTANT_BUFFER vertex_constant_buffer;
  {
    float L = draw_data->DisplayPos.x;
    float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
    float T = draw_data->DisplayPos.y;
    float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
    float mvp[4][4] =
    {
        { 2.0f / (R - L),   0.0f,           0.0f,       0.0f },
        { 0.0f,         2.0f / (T - B),     0.0f,       0.0f },
        { 0.0f,         0.0f,           0.5f,       0.0f },
        { (R + L) / (L - R),  (T + B) / (B - T),    0.5f,       1.0f },
    };
    memcpy(&vertex_constant_buffer.mvp, mvp, sizeof(mvp));
  }

  // Setup viewport
  D3D12_VIEWPORT vp;
  memset(&vp, 0, sizeof(D3D12_VIEWPORT));
  vp.Width = draw_data->DisplaySize.x;
  vp.Height = draw_data->DisplaySize.y;
  vp.MinDepth = 0.0f;
  vp.MaxDepth = 1.0f;
  vp.TopLeftX = vp.TopLeftY = 0.0f;
  ctx->RSSetViewports(1, &vp);

  // Bind shader and vertex buffers
  unsigned int stride = sizeof(ImDrawVert);
  unsigned int offset = 0;
  D3D12_VERTEX_BUFFER_VIEW vbv;
  memset(&vbv, 0, sizeof(D3D12_VERTEX_BUFFER_VIEW));
  vbv.BufferLocation = fr->VertexBuffer->GetGPUVirtualAddress() + offset;
  vbv.SizeInBytes = fr->VertexBufferSize * stride;
  vbv.StrideInBytes = stride;
  ctx->IASetVertexBuffers(0, 1, &vbv);
  D3D12_INDEX_BUFFER_VIEW ibv;
  memset(&ibv, 0, sizeof(D3D12_INDEX_BUFFER_VIEW));
  ibv.BufferLocation = fr->IndexBuffer->GetGPUVirtualAddress();
  ibv.SizeInBytes = fr->IndexBufferSize * sizeof(ImDrawIdx);
  ibv.Format = sizeof(ImDrawIdx) == 2 ? DXGI_FORMAT_R16_UINT : DXGI_FORMAT_R32_UINT;
  ctx->IASetIndexBuffer(&ibv);
  ctx->IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
  ctx->SetPipelineState(g_pPipelineState);
  ctx->SetGraphicsRootSignature(g_pRootSignature);
  ctx->SetGraphicsRoot32BitConstants(0, 16, &vertex_constant_buffer, 0);

  // Setup blend factor
  const float blend_factor[4] = { 0.f, 0.f, 0.f, 0.f };
  ctx->OMSetBlendFactor(blend_factor);
}

// Render function
void ImGui_ImplDX12_RenderDrawData(ImDrawData* draw_data, ID3D12GraphicsCommandList* ctx)
{
  // Avoid rendering when minimized
  if (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f)
    return;

  // FIXME: I'm assuming that this only gets called once per frame!
  // If not, we can't just re-allocate the IB or VB, we'll have to do a proper allocator.
  g_frameIndex = g_frameIndex + 1;
  FrameResources* fr = &g_pFrameResources[g_frameIndex % g_numFramesInFlight];

  // Create and grow vertex/index buffers if needed
  if (fr->VertexBuffer == NULL || fr->VertexBufferSize < draw_data->TotalVtxCount)
  {
    SafeRelease(fr->VertexBuffer);
    fr->VertexBufferSize = draw_data->TotalVtxCount + 5000;
    D3D12_HEAP_PROPERTIES props;
    memset(&props, 0, sizeof(D3D12_HEAP_PROPERTIES));
    props.Type = D3D12_HEAP_TYPE_UPLOAD;
    props.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
    props.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;
    D3D12_RESOURCE_DESC desc;
    memset(&desc, 0, sizeof(D3D12_RESOURCE_DESC));
    desc.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
    desc.Width = fr->VertexBufferSize * sizeof(ImDrawVert);
    desc.Height = 1;
    desc.DepthOrArraySize = 1;
    desc.MipLevels = 1;
    desc.Format = DXGI_FORMAT_UNKNOWN;
    desc.SampleDesc.Count = 1;
    desc.Layout = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
    desc.Flags = D3D12_RESOURCE_FLAG_NONE;
    if (g_pd3dDevice->CreateCommittedResource(&props, D3D12_HEAP_FLAG_NONE, &desc, D3D12_RESOURCE_STATE_GENERIC_READ, NULL, IID_PPV_ARGS(&fr->VertexBuffer)) < 0)
      return;
  }
  if (fr->IndexBuffer == NULL || fr->IndexBufferSize < draw_data->TotalIdxCount)
  {
    SafeRelease(fr->IndexBuffer);
    fr->IndexBufferSize = draw_data->TotalIdxCount + 10000;
    D3D12_HEAP_PROPERTIES props;
    memset(&props, 0, sizeof(D3D12_HEAP_PROPERTIES));
    props.Type = D3D12_HEAP_TYPE_UPLOAD;
    props.CPUPageProperty = D3D12_CPU_PAGE_PROPERTY_UNKNOWN;
    props.MemoryPoolPreference = D3D12_MEMORY_POOL_UNKNOWN;
    D3D12_RESOURCE_DESC desc;
    memset(&desc, 0, sizeof(D3D12_RESOURCE_DESC));
    desc.Dimension = D3D12_RESOURCE_DIMENSION_BUFFER;
    desc.Width = fr->IndexBufferSize * sizeof(ImDrawIdx);
    desc.Height = 1;
    desc.DepthOrArraySize = 1;
    desc.MipLevels = 1;
    desc.Format = DXGI_FORMAT_UNKNOWN;
    desc.SampleDesc.Count = 1;
    desc.Layout = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
    desc.Flags = D3D12_RESOURCE_FLAG_NONE;
    if (g_pd3dDevice->CreateCommittedResource(&props, D3D12_HEAP_FLAG_NONE, &desc, D3D12_RESOURCE_STATE_GENERIC_READ, NULL, IID_PPV_ARGS(&fr->IndexBuffer)) < 0)
      return;
  }

  // Upload vertex/index data into a single contiguous GPU buffer
  void* vtx_resource, * idx_resource;
  D3D12_RANGE range;
  memset(&range, 0, sizeof(D3D12_RANGE));
  if (fr->VertexBuffer->Map(0, &range, &vtx_resource) != S_OK)
    return;
  if (fr->IndexBuffer->Map(0, &range, &idx_resource) != S_OK)
    return;
  ImDrawVert* vtx_dst = (ImDrawVert*)vtx_resource;
  ImDrawIdx* idx_dst = (ImDrawIdx*)idx_resource;
  for (int n = 0; n < draw_data->CmdListsCount; n++)
  {
    const ImDrawList* cmd_list = draw_data->CmdLists[n];
    memcpy(vtx_dst, cmd_list->VtxBuffer.Data, cmd_list->VtxBuffer.Size * sizeof(ImDrawVert));
    memcpy(idx_dst, cmd_list->IdxBuffer.Data, cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx));
    vtx_dst += cmd_list->VtxBuffer.Size;
    idx_dst += cmd_list->IdxBuffer.Size;
  }
  fr->VertexBuffer->Unmap(0, &range);
  fr->IndexBuffer->Unmap(0, &range);

  // Setup desired DX state
  ImGui_ImplDX12_SetupRenderState(draw_data, ctx, fr);

  // Render command lists
  // (Because we merged all buffers into a single one, we maintain our own offset into them)
  int global_vtx_offset = 0;
  int global_idx_offset = 0;
  ImVec2 clip_off = draw_data->DisplayPos;
  for (int n = 0; n < draw_data->CmdListsCount; n++)
  {
    const ImDrawList* cmd_list = draw_data->CmdLists[n];
    for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
    {
      const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
      if (pcmd->UserCallback != NULL)
      {
        // User callback, registered via ImDrawList::AddCallback()
        // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
        if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
          ImGui_ImplDX12_SetupRenderState(draw_data, ctx, fr);
        else
          pcmd->UserCallback(cmd_list, pcmd);
      }
      else
      {
        // Apply Scissor, Bind texture, Draw
        const D3D12_RECT r = { (LONG)(pcmd->ClipRect.x - clip_off.x), (LONG)(pcmd->ClipRect.y - clip_off.y), (LONG)(pcmd->ClipRect.z - clip_off.x), (LONG)(pcmd->ClipRect.w - clip_off.y) };
        if (r.right > r.left && r.bottom > r.top)
        {
          ctx->SetGraphicsRootDescriptorTable(1, reinterpret_cast<D3D12::Texture*>(pcmd->TextureId)->GetSRVDescriptor());
          ctx->RSSetScissorRects(1, &r);
          ctx->DrawIndexedInstanced(pcmd->ElemCount, 1, pcmd->IdxOffset + global_idx_offset, pcmd->VtxOffset + global_vtx_offset, 0);
        }
      }
    }
    global_idx_offset += cmd_list->IdxBuffer.Size;
    global_vtx_offset += cmd_list->VtxBuffer.Size;
  }
}

bool ImGui_ImplDX12_CreateFontsTexture()
{
  // Build texture atlas
  ImGuiIO & io = ImGui::GetIO();
  unsigned char* pixels;
  int width, height;
  io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
  
  // Upload texture to graphics system
  D3D12::Texture texture;
  if (!texture.Create(width, height, 1, DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_FORMAT_UNKNOWN, DXGI_FORMAT_UNKNOWN, D3D12_RESOURCE_FLAG_NONE) ||
      !texture.LoadData(0, 0, width, height, pixels, width * sizeof(u32)))
  {
    return false;
  }

  g_FontTexture = std::move(texture);
  
  // Store our identifier
  io.Fonts->TexID = reinterpret_cast<ImTextureID>(&g_FontTexture);
  return true;
}

bool    ImGui_ImplDX12_CreateDeviceObjects()
{
  if (!g_pd3dDevice)
    return false;
  if (g_pPipelineState)
    ImGui_ImplDX12_InvalidateDeviceObjects();

  // Create the root signature
  {
    D3D12_DESCRIPTOR_RANGE descRange = {};
    descRange.RangeType = D3D12_DESCRIPTOR_RANGE_TYPE_SRV;
    descRange.NumDescriptors = 1;
    descRange.BaseShaderRegister = 0;
    descRange.RegisterSpace = 0;
    descRange.OffsetInDescriptorsFromTableStart = 0;

    D3D12_ROOT_PARAMETER param[2] = {};

    param[0].ParameterType = D3D12_ROOT_PARAMETER_TYPE_32BIT_CONSTANTS;
    param[0].Constants.ShaderRegister = 0;
    param[0].Constants.RegisterSpace = 0;
    param[0].Constants.Num32BitValues = 16;
    param[0].ShaderVisibility = D3D12_SHADER_VISIBILITY_VERTEX;

    param[1].ParameterType = D3D12_ROOT_PARAMETER_TYPE_DESCRIPTOR_TABLE;
    param[1].DescriptorTable.NumDescriptorRanges = 1;
    param[1].DescriptorTable.pDescriptorRanges = &descRange;
    param[1].ShaderVisibility = D3D12_SHADER_VISIBILITY_PIXEL;

    D3D12_STATIC_SAMPLER_DESC staticSampler = {};
    staticSampler.Filter = D3D12_FILTER_MIN_MAG_MIP_LINEAR;
    staticSampler.AddressU = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
    staticSampler.AddressV = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
    staticSampler.AddressW = D3D12_TEXTURE_ADDRESS_MODE_WRAP;
    staticSampler.MipLODBias = 0.f;
    staticSampler.MaxAnisotropy = 0;
    staticSampler.ComparisonFunc = D3D12_COMPARISON_FUNC_ALWAYS;
    staticSampler.BorderColor = D3D12_STATIC_BORDER_COLOR_TRANSPARENT_BLACK;
    staticSampler.MinLOD = 0.f;
    staticSampler.MaxLOD = 0.f;
    staticSampler.ShaderRegister = 0;
    staticSampler.RegisterSpace = 0;
    staticSampler.ShaderVisibility = D3D12_SHADER_VISIBILITY_PIXEL;

    D3D12_ROOT_SIGNATURE_DESC desc = {};
    desc.NumParameters = _countof(param);
    desc.pParameters = param;
    desc.NumStaticSamplers = 1;
    desc.pStaticSamplers = &staticSampler;
    desc.Flags =
      D3D12_ROOT_SIGNATURE_FLAG_ALLOW_INPUT_ASSEMBLER_INPUT_LAYOUT |
      D3D12_ROOT_SIGNATURE_FLAG_DENY_HULL_SHADER_ROOT_ACCESS |
      D3D12_ROOT_SIGNATURE_FLAG_DENY_DOMAIN_SHADER_ROOT_ACCESS |
      D3D12_ROOT_SIGNATURE_FLAG_DENY_GEOMETRY_SHADER_ROOT_ACCESS;

    auto blob = g_d3d12_context->SerializeRootSignature(&desc);
    if (!blob)
      return false;

    g_pd3dDevice->CreateRootSignature(0, blob->GetBufferPointer(), blob->GetBufferSize(), IID_PPV_ARGS(&g_pRootSignature));
  }

  // By using D3DCompile() from <d3dcompiler.h> / d3dcompiler.lib, we introduce a dependency to a given version of d3dcompiler_XX.dll (see D3DCOMPILER_DLL_A)
  // If you would like to use this DX12 sample code but remove this dependency you can:
  //  1) compile once, save the compiled shader blobs into a file or source code and pass them to CreateVertexShader()/CreatePixelShader() [preferred solution]
  //  2) use code to detect any version of the DLL and grab a pointer to D3DCompile from the DLL.
  // See https://github.com/ocornut/imgui/pull/638 for sources and details.

  D3D12_GRAPHICS_PIPELINE_STATE_DESC psoDesc;
  memset(&psoDesc, 0, sizeof(D3D12_GRAPHICS_PIPELINE_STATE_DESC));
  psoDesc.NodeMask = 1;
  psoDesc.PrimitiveTopologyType = D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE;
  psoDesc.pRootSignature = g_pRootSignature;
  psoDesc.SampleMask = UINT_MAX;
  psoDesc.NumRenderTargets = 1;
  psoDesc.RTVFormats[0] = g_RTVFormat;
  psoDesc.SampleDesc.Count = 1;
  psoDesc.Flags = D3D12_PIPELINE_STATE_FLAG_NONE;

  ID3DBlob* vertexShaderBlob;
  ID3DBlob* pixelShaderBlob;

  // Create the vertex shader
  {
    static const char* vertexShader =
      "cbuffer vertexBuffer : register(b0) \
            {\
              float4x4 ProjectionMatrix; \
            };\
            struct VS_INPUT\
            {\
              float2 pos : POSITION;\
              float4 col : COLOR0;\
              float2 uv  : TEXCOORD0;\
            };\
            \
            struct PS_INPUT\
            {\
              float4 pos : SV_POSITION;\
              float4 col : COLOR0;\
              float2 uv  : TEXCOORD0;\
            };\
            \
            PS_INPUT main(VS_INPUT input)\
            {\
              PS_INPUT output;\
              output.pos = mul( ProjectionMatrix, float4(input.pos.xy, 0.f, 1.f));\
              output.col = input.col;\
              output.uv  = input.uv;\
              return output;\
            }";

    if (FAILED(D3DCompile(vertexShader, strlen(vertexShader), NULL, NULL, NULL, "main", "vs_5_0", 0, 0, &vertexShaderBlob, NULL)))
      return false; // NB: Pass ID3D10Blob* pErrorBlob to D3DCompile() to get error showing in (const char*)pErrorBlob->GetBufferPointer(). Make sure to Release() the blob!
    psoDesc.VS = { vertexShaderBlob->GetBufferPointer(), vertexShaderBlob->GetBufferSize() };

    // Create the input layout
    static D3D12_INPUT_ELEMENT_DESC local_layout[] =
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32_FLOAT,   0, (UINT)IM_OFFSETOF(ImDrawVert, pos), D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
        { "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT,   0, (UINT)IM_OFFSETOF(ImDrawVert, uv),  D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
        { "COLOR",    0, DXGI_FORMAT_R8G8B8A8_UNORM, 0, (UINT)IM_OFFSETOF(ImDrawVert, col), D3D12_INPUT_CLASSIFICATION_PER_VERTEX_DATA, 0 },
    };
    psoDesc.InputLayout = { local_layout, 3 };
  }

  // Create the pixel shader
  {
    static const char* pixelShader =
      "struct PS_INPUT\
            {\
              float4 pos : SV_POSITION;\
              float4 col : COLOR0;\
              float2 uv  : TEXCOORD0;\
            };\
            SamplerState sampler0 : register(s0);\
            Texture2D texture0 : register(t0);\
            \
            float4 main(PS_INPUT input) : SV_Target\
            {\
              float4 out_col = input.col * texture0.Sample(sampler0, input.uv); \
              return out_col; \
            }";

    if (FAILED(D3DCompile(pixelShader, strlen(pixelShader), NULL, NULL, NULL, "main", "ps_5_0", 0, 0, &pixelShaderBlob, NULL)))
    {
      vertexShaderBlob->Release();
      return false; // NB: Pass ID3D10Blob* pErrorBlob to D3DCompile() to get error showing in (const char*)pErrorBlob->GetBufferPointer(). Make sure to Release() the blob!
    }
    psoDesc.PS = { pixelShaderBlob->GetBufferPointer(), pixelShaderBlob->GetBufferSize() };
  }

  // Create the blending setup
  {
    D3D12_BLEND_DESC& desc = psoDesc.BlendState;
    desc.AlphaToCoverageEnable = false;
    desc.RenderTarget[0].BlendEnable = true;
    desc.RenderTarget[0].SrcBlend = D3D12_BLEND_SRC_ALPHA;
    desc.RenderTarget[0].DestBlend = D3D12_BLEND_INV_SRC_ALPHA;
    desc.RenderTarget[0].BlendOp = D3D12_BLEND_OP_ADD;
    desc.RenderTarget[0].SrcBlendAlpha = D3D12_BLEND_INV_SRC_ALPHA;
    desc.RenderTarget[0].DestBlendAlpha = D3D12_BLEND_ZERO;
    desc.RenderTarget[0].BlendOpAlpha = D3D12_BLEND_OP_ADD;
    desc.RenderTarget[0].RenderTargetWriteMask = D3D12_COLOR_WRITE_ENABLE_ALL;
  }

  // Create the rasterizer state
  {
    D3D12_RASTERIZER_DESC& desc = psoDesc.RasterizerState;
    desc.FillMode = D3D12_FILL_MODE_SOLID;
    desc.CullMode = D3D12_CULL_MODE_NONE;
    desc.FrontCounterClockwise = FALSE;
    desc.DepthBias = D3D12_DEFAULT_DEPTH_BIAS;
    desc.DepthBiasClamp = D3D12_DEFAULT_DEPTH_BIAS_CLAMP;
    desc.SlopeScaledDepthBias = D3D12_DEFAULT_SLOPE_SCALED_DEPTH_BIAS;
    desc.DepthClipEnable = true;
    desc.MultisampleEnable = FALSE;
    desc.AntialiasedLineEnable = FALSE;
    desc.ForcedSampleCount = 0;
    desc.ConservativeRaster = D3D12_CONSERVATIVE_RASTERIZATION_MODE_OFF;
  }

  // Create depth-stencil State
  {
    D3D12_DEPTH_STENCIL_DESC& desc = psoDesc.DepthStencilState;
    desc.DepthEnable = false;
    desc.DepthWriteMask = D3D12_DEPTH_WRITE_MASK_ALL;
    desc.DepthFunc = D3D12_COMPARISON_FUNC_ALWAYS;
    desc.StencilEnable = false;
    desc.FrontFace.StencilFailOp = desc.FrontFace.StencilDepthFailOp = desc.FrontFace.StencilPassOp = D3D12_STENCIL_OP_KEEP;
    desc.FrontFace.StencilFunc = D3D12_COMPARISON_FUNC_ALWAYS;
    desc.BackFace = desc.FrontFace;
  }

  HRESULT result_pipeline_state = g_pd3dDevice->CreateGraphicsPipelineState(&psoDesc, IID_PPV_ARGS(&g_pPipelineState));
  vertexShaderBlob->Release();
  pixelShaderBlob->Release();
  if (result_pipeline_state != S_OK)
    return false;

  return true;
}

void    ImGui_ImplDX12_InvalidateDeviceObjects()
{
  if (!g_pd3dDevice)
    return;

  SafeRelease(g_pRootSignature);
  SafeRelease(g_pPipelineState);
  g_FontTexture.Destroy(true);

  ImGuiIO& io = ImGui::GetIO();
  io.Fonts->SetTexID(NULL); // We copied g_pFontTextureView to io.Fonts->TexID so let's clear that as well.

  for (UINT i = 0; i < g_numFramesInFlight; i++)
  {
    FrameResources* fr = &g_pFrameResources[i];
    SafeRelease(fr->IndexBuffer);
    SafeRelease(fr->VertexBuffer);
  }
}

bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FORMAT rtv_format)
{
  // Setup backend capabilities flags
  ImGuiIO& io = ImGui::GetIO();
  io.BackendRendererName = "imgui_impl_dx12";
  io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

  g_pd3dDevice = device;
  g_RTVFormat = rtv_format;
  g_pFrameResources = new FrameResources[num_frames_in_flight];
  g_numFramesInFlight = num_frames_in_flight;
  g_frameIndex = UINT_MAX;

  // Create buffers with a default size (they will later be grown as needed)
  for (int i = 0; i < num_frames_in_flight; i++)
  {
    FrameResources* fr = &g_pFrameResources[i];
    fr->IndexBuffer = NULL;
    fr->VertexBuffer = NULL;
    fr->IndexBufferSize = 10000;
    fr->VertexBufferSize = 5000;
  }

  return ImGui_ImplDX12_CreateDeviceObjects();
}

void ImGui_ImplDX12_Shutdown()
{
  ImGui_ImplDX12_InvalidateDeviceObjects();
  delete[] g_pFrameResources;
  g_pFrameResources = NULL;
  g_pd3dDevice = NULL;
  g_numFramesInFlight = 0;
  g_frameIndex = UINT_MAX;
}
